Sourdough Blueberry Coffee Cake

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I took my popular Sourdough Coffee Cake, and made it even better with a thick layer of juicy blueberries baked right into the center. This Sourdough Blueberry Coffee Cake is soft, buttery, topped with a golden crumble, and finished with a bright blueberry lemon glaze that makes it impossible to stop at just one slice!

Tools You’ll Need:

1. Mixing bowls- for the cake batter, crumble, blueberry layer, and glaze. I love this set of glass mixing bowls with lids for fermenting my cake batters!
2. Whisk- for mixing the batter and glaze.
3. Digital kitchen scale (optional)– for accurate measuring, especially helpful with sourdough baking. I linked the one I like here.
4. Measuring cups and spoons– for measuring ingredients.
5. Fork or pastry blender- for mixing the crumble.
6. Spatula- to spread the batter in the cake pan.
7. 9×13-inch or 9×9 inch baking pan- for baking the coffee cake. For a thinner coffee cake, use a 9×13 baking pan. If you want a taller cake, you can use a 9×9 cake pan. I love these USA 9×9 baking pans that have a nice tall edge for this type of cake and aluminized steel that gives the most perfectly even bake!
8. Parchment paper- to line the cake pan to avoid sticking.

Gather Your Ingredients:

1. Sourdough Starter- (flat or past peak, can be cold or room temperature). Adds depth of flavor and moisture without making this cake “sour”. Key for fermentation if you choose to ferment the batter.
2. All-purpose Flour- Gives cake structure and keeps the crumb tender. You can also substitute for cake flour.
3. Buttermilk or milk- Lightens the batter and keeps the crumb soft. I personally highly recommend using buttermilk, the texture and tenderness is so lovely. If you don’t have it though, you can substitute with whole milk.
4. Avocado Oil- Adds moisture and keeps the cake soft and tender. You can substitute for any neutral cooking oil.
5. Sour Cream- this is key to a moist cake! You can also substitute this for full-fat Greek yogurt.
6. White Sugar– Sweetens the cake, filling, and crumble.
7. Brown Sugar- for that classic coffee cake flavor.
8. Vanilla extract– Enhances the flavor and brings warmth.
9. Eggs (room temperature)– provide structure and lift with moisture, works as a binder for ingredients.
10. Baking powder + Baking soda– Ensures the right rise and tenderness.
11. Salt- Balances sweetness and enhances all the other flavors.
12. Salted Butter- Binds the crumble together for the perfect texture.
13. Powdered Sugar- Sweetens and stabilizes the glaze. Do not use granulated sugar or your icing will be grainy.
14. Blueberries- I used fresh blueberries and this is what I would recommend for the best texture, but you can use frozen in a pinch. I will list how to use frozen blueberries in the recipe, smaller blueberry varieties tend to work best in batter to release less moisture but any will work.
15. Lemons (optional)- lemon juice and zest brightens the batter and glaze that I love, you can skip this if you’d like.

Instructions

Step 1: Mix The Cake Batter

In a mixing bowl, add the white sugar, brown sugar, sourdough starter or discard, sour cream, milk, oil, eggs, lemon zest, and vanilla. Whisk the wet ingredients until smooth.

Add your flour, baking powder, baking soda, and salt to the bowl. Whisk in the dry ingredients until just combined, and no flour streaks remain. It’s important once you add the flour to avoid overmixing!

Optional Overnight Fermentation: Cover the bowl with plastic wrap or a lid, and refrigerate overnight. This step is key in your fermentation process. If you want to shorten your fermentation time, you can allow the batter to rest for 4 hours at room temperature for a same day bake. I don’t advise leaving this batter at room temperature overnight, its too hydrated and will overproof.

Step 2: Mix The Ripple and BLueberry Filling

To make the crumble topping, add the butter to a microwave safe bowl and melt it.

Add the white sugar and flour to the melted butter. Using a fork or a spoon, combine the crumble mixture until it’s clumpy and crumbly. Set aside for later.

In another bowl, add the blueberries, flour, and white sugar . Gently mix to combine all of the ingredients for the blueberry filling and set aside for later.

To use frozen blueberries: Weigh out frozen blueberries and allow to rest in a bowl of warm water to thaw. After about 5-10 minutes, strain the blueberries from water and transfer them to a bowl lined with a paper towel to absorb any excess moisture (you can also just strain and blot). After water has been absorbed, remove the paper towel and toss the blueberries in the flour and sugar.

Step 3: Assemble the Cake

Fermentation Note: If you fermented the batter overnight in the refrigerator, allow the bowl of batter to rest on the counter for roughly 1 hour. This is a key step to achieving a tender crumb, don’t skip this step! If you like temperature cues, the temperature of the batter should read roughly 70 F before proceeding.

Note on choosing a pan: I used a 9×9 pan, but this will make the bake time longer as the cake is thicker but I love the thickness of the layers. I’m listing directions on how to make a 9×9 cake or a 9×13 cake, the directions will vary. If you use a dark metal pan the cake may brown more on the edges and glass pans take much longer to bake the cake. I recommend a light metal pan for best results.

Preheat your oven to 350°F. Line your 9×13 or 9×9 cake pan with parchment paper (this helps to remove the cake easily), and spray lightly with cooking oil.

For a 9×9 cake: Scoop half of the cake batter into the cake pan, and gently use a spatula spread the batter to the edges to make sure the bottom of the cake pan is covered with the batter.

Sprinkle the blueberries evenly over the top of the cake batter (hold back one handful for the top of the cake). Sprinkle the remaining sugar and flour in the bowl over the top of the blueberries.

Scoop the rest of the cake batter on top of the blueberry layer, and use a spatula to spread the batter to meet the edges of the pan.

Sprinkle the crumble evenly over the top of the cake, making sure to cover the edges. Sprinkle the remaining blueberries over the top of the crumble.

For a 9×13 cake: If you use a 9×13 cake pan, add all of the cake batter to the pan that you prepared. Add the blueberries over the top, reserving one handful for the top. Sprinkle the excess flour over the blueberries. Add the crumble on top and sprinkle the remaining blueberries on top.

Step 4: Bake the Cake

Transfer the cake to the preheated oven. If you’re cake is in a 9×13 cake pan, you’ll bake this cake for about 60 minutes.

You’ll want to check then center with a toothpick around 40 minutes, and bake the cake until a toothpick comes out clean with just a few loose crumbs. Do not remove the cake if you see wet batter!

Internal temeprature of the cake should be 200 F in the center when it’s done. The bake time is a general guide go off of visuals and internal temperature for the best results.

9×9 pan baking note: If you used a 9×9 cake pan, this cake typically needs 75-90 minutes of bake time to fully cook the center as the cake is taller and more dense.

Remove the cake from the oven as soon as it’s finished baking, and allow it to cool completely before glazing.

Step 5: Glaze the Coffee Cake

In a small bowl, add the blueberries (fresh or frozen) and microwave for 30 seconds. Remove the skins with a fork and mash the blueberries up.

Add the powdered sugar and lemon juice to the blueberries.

Note: lemon juice will make the glaze more pink and you can swap the lemon juice for milk if you prefer.

Start to whisk the glaze and bring it together, and add the milk or half and half one teaspoon at a time while you’re whisking until the glaze has reached you’re desired consistency.

You want the glaze to still be thick, but able to slowly run off the spoon.

Drizzle the glaze over the top of the cooled coffee cake. Allow the glaze to set up for about 15-20 minutes before slicing and serving!

Yields 9-12 slices of cake (depending on cake pan size)

How to Store:

Room temperature: Store on the counter in an airtight container up to 2 day. Because of the blueberries, this cake is best refrigerated.

Refrigerator: For longer storage, refrigerate in an air tight container for up to 5 days. The blueberry layer keeps it extra moist.

Freezer: Store in the freezer in an airtight container for up to 3 weeks. Gently thaw on the counter and reheat gently in the microwave at 15 second intervals or in the oven at 350 F until cake is warmed.

FAQ’s

Drop a comment and leave a star review if you loved this recipe, and don’t forget to try more of my sourdough cake recipes!

Sourdough Cake Recipes:

• Sourdough Vanilla Cake (moist and fluffy!)
• Sourdough Brown Butter Carrot Cake
• Sourdough Chocolate Cake
• Sourdough Lemon Cake